Inline Julia code to define fig-cap using Jupyter kernel and Quarto 1.4 pre-release?

[dcnorris]

Description

I see that the 1.4 pre-release supports "executing inline expressions when using Jupyter kernels." Indeed, I can get Julia code to execute inside the main text:

(Mean ESS across all parameters: `{julia} @sprintf "%3.f" mean_ess`.)

[Please don't @ me about computing a mean ESS ;).]

But I cannot make this work to obtain a computed fig-cap setting. I've seemingly exhausted the possible syntactical permutations, and suspect this is not yet supported for Julia; would anyone confirm or deny this?

[cscheid]

But I cannot make this work to obtain a computed fig-cap setting.

Can you share a full, minimal example?

[dcnorris]

(I'm using quarto v1.4.267.)

---
title: "Trouble computing fig-cap with Julia"
author: David C. Norris
format:
  html:
    code-fold: true
    self-contained: true
jupyter: julia-1.9
---

```{julia}
n = 10
using Plots
```

### This first plot caption comes out saying:

> {julia} "Plot of numbers 1 thru $n."

```{julia}
#| label: too-bad
#| fig-cap: '`{julia} "Plot of numbers 1 thru $n."`'

plot(1:n)
```

### The next 2 plots get captions that read:

> [object Object]

```{julia}
#| label: too-bad-2
#| fig-cap: !expr '{julia} "Plot of numbers 1 thru $n."'

plot(1:n)
```

```{julia}
#| label: too-bad-3
#| fig-cap: !expr '`{julia} "Plot of numbers 1 thru $n."`'

plot(1:n)
```

[cscheid]

Thanks. I just wanted to make sure.

#| fig-cap: '{julia} "Plot of numbers 1 thru $n."'

This is not a feature that exists. (Did we imply this feature exists in our docs? If so, we should fix that.)

[mcanouil]

To date, the only piece of documentation regarding this two weeks old feature is https://quarto.org/docs/prerelease/1.4/inline.html.
And some parts are missing such as how to escape the inline commands for educational purposes.

[dcnorris]

Your docs didn't claim this feature exists, but they also didn't say it doesn't. Since this sort of thing is possible with R, perhaps you would do well to clarify it's not yet implemented for Julia.

[dcnorris]

Referencing $N$'s in figure captions is a basic requirement for reproducible research. Is there a workaround one might use in the meantime?

[baptiste]

You could use custom LaTeX macros to get around this,

---
title: "Untitled"
format: html
---

```{r}
#| echo: false
#| results: asis
N <- 1234
cat(paste0("$\\newcommand{\\mycaptionN}{",N,"}$"))
```


```{r}
#| label: too-bad
#| fig-cap: The value is $\mycaptionN$
plot(1:3)
```

Obviously a hack, but I think the approach could be extended via Lua filters (or something built-in), basically having placeholders that are replaced once the variables are known. In this case pandoc is doing the macro substitution, as a side-effect of how it handles maths.

[mcanouil]

@baptiste could you edit your example to only use one code cell options syntax, preferably the YAML syntax recommended in Quarto?

[cderv]

Your docs didn't claim this feature exists, but they also didn't say it doesn't. Since this sort of thing is possible with R, perhaps you would do well to clarify it's not yet implemented for Julia.

@dcnorris Regarding our doc, we currently only mention in the R computation doc the !expr syntax as a way to use R expression in YAML
https://quarto.org/docs/computations/r.html#chunk-options

We could try to clarify that this is really not working for other language, but by the fact it is in the engine: knitr doc only we though it was clear it is not working for others like engine: jupyter. Do you have a suggestion ?

[dcnorris]

My attempts to use !expr were just hacking away, hoping something would work. Pending the actual release of 1.4, you might just explicitly state — at the point where you mention this new feature https://quarto.org/docs/prerelease/1.4/inline.html — that it cannot be used in YAML strings.